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Merge rsync://rsync.kernel.org/pub/scm/linux/kernel/git/dtor/input.git manually
[deliverable/linux.git] / net / ipv4 / ip_output.c
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * The Internet Protocol (IP) output module.
7 *
8 * Version: $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $
9 *
10 * Authors: Ross Biro
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Donald Becker, <becker@super.org>
13 * Alan Cox, <Alan.Cox@linux.org>
14 * Richard Underwood
15 * Stefan Becker, <stefanb@yello.ping.de>
16 * Jorge Cwik, <jorge@laser.satlink.net>
17 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
18 * Hirokazu Takahashi, <taka@valinux.co.jp>
19 *
20 * See ip_input.c for original log
21 *
22 * Fixes:
23 * Alan Cox : Missing nonblock feature in ip_build_xmit.
24 * Mike Kilburn : htons() missing in ip_build_xmit.
25 * Bradford Johnson: Fix faulty handling of some frames when
26 * no route is found.
27 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
28 * (in case if packet not accepted by
29 * output firewall rules)
30 * Mike McLagan : Routing by source
31 * Alexey Kuznetsov: use new route cache
32 * Andi Kleen: Fix broken PMTU recovery and remove
33 * some redundant tests.
34 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
35 * Andi Kleen : Replace ip_reply with ip_send_reply.
36 * Andi Kleen : Split fast and slow ip_build_xmit path
37 * for decreased register pressure on x86
38 * and more readibility.
39 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
40 * silently drop skb instead of failing with -EPERM.
41 * Detlev Wengorz : Copy protocol for fragments.
42 * Hirokazu Takahashi: HW checksumming for outgoing UDP
43 * datagrams.
44 * Hirokazu Takahashi: sendfile() on UDP works now.
45 */
46
47 #include <asm/uaccess.h>
48 #include <asm/system.h>
49 #include <linux/module.h>
50 #include <linux/types.h>
51 #include <linux/kernel.h>
52 #include <linux/sched.h>
53 #include <linux/mm.h>
54 #include <linux/string.h>
55 #include <linux/errno.h>
56 #include <linux/config.h>
57
58 #include <linux/socket.h>
59 #include <linux/sockios.h>
60 #include <linux/in.h>
61 #include <linux/inet.h>
62 #include <linux/netdevice.h>
63 #include <linux/etherdevice.h>
64 #include <linux/proc_fs.h>
65 #include <linux/stat.h>
66 #include <linux/init.h>
67
68 #include <net/snmp.h>
69 #include <net/ip.h>
70 #include <net/protocol.h>
71 #include <net/route.h>
72 #include <net/tcp.h>
73 #include <net/udp.h>
74 #include <linux/skbuff.h>
75 #include <net/sock.h>
76 #include <net/arp.h>
77 #include <net/icmp.h>
78 #include <net/raw.h>
79 #include <net/checksum.h>
80 #include <net/inetpeer.h>
81 #include <net/checksum.h>
82 #include <linux/igmp.h>
83 #include <linux/netfilter_ipv4.h>
84 #include <linux/netfilter_bridge.h>
85 #include <linux/mroute.h>
86 #include <linux/netlink.h>
87
88 /*
89 * Shall we try to damage output packets if routing dev changes?
90 */
91
92 int sysctl_ip_dynaddr;
93 int sysctl_ip_default_ttl = IPDEFTTL;
94
95 /* Generate a checksum for an outgoing IP datagram. */
96 __inline__ void ip_send_check(struct iphdr *iph)
97 {
98 iph->check = 0;
99 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
100 }
101
102 /* dev_loopback_xmit for use with netfilter. */
103 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
104 {
105 newskb->mac.raw = newskb->data;
106 __skb_pull(newskb, newskb->nh.raw - newskb->data);
107 newskb->pkt_type = PACKET_LOOPBACK;
108 newskb->ip_summed = CHECKSUM_UNNECESSARY;
109 BUG_TRAP(newskb->dst);
110 nf_reset(newskb);
111 netif_rx(newskb);
112 return 0;
113 }
114
115 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
116 {
117 int ttl = inet->uc_ttl;
118
119 if (ttl < 0)
120 ttl = dst_metric(dst, RTAX_HOPLIMIT);
121 return ttl;
122 }
123
124 /*
125 * Add an ip header to a skbuff and send it out.
126 *
127 */
128 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
129 u32 saddr, u32 daddr, struct ip_options *opt)
130 {
131 struct inet_sock *inet = inet_sk(sk);
132 struct rtable *rt = (struct rtable *)skb->dst;
133 struct iphdr *iph;
134
135 /* Build the IP header. */
136 if (opt)
137 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen);
138 else
139 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr));
140
141 iph->version = 4;
142 iph->ihl = 5;
143 iph->tos = inet->tos;
144 if (ip_dont_fragment(sk, &rt->u.dst))
145 iph->frag_off = htons(IP_DF);
146 else
147 iph->frag_off = 0;
148 iph->ttl = ip_select_ttl(inet, &rt->u.dst);
149 iph->daddr = rt->rt_dst;
150 iph->saddr = rt->rt_src;
151 iph->protocol = sk->sk_protocol;
152 iph->tot_len = htons(skb->len);
153 ip_select_ident(iph, &rt->u.dst, sk);
154 skb->nh.iph = iph;
155
156 if (opt && opt->optlen) {
157 iph->ihl += opt->optlen>>2;
158 ip_options_build(skb, opt, daddr, rt, 0);
159 }
160 ip_send_check(iph);
161
162 skb->priority = sk->sk_priority;
163
164 /* Send it out. */
165 return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
166 dst_output);
167 }
168
169 static inline int ip_finish_output2(struct sk_buff *skb)
170 {
171 struct dst_entry *dst = skb->dst;
172 struct hh_cache *hh = dst->hh;
173 struct net_device *dev = dst->dev;
174 int hh_len = LL_RESERVED_SPACE(dev);
175
176 /* Be paranoid, rather than too clever. */
177 if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
178 struct sk_buff *skb2;
179
180 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
181 if (skb2 == NULL) {
182 kfree_skb(skb);
183 return -ENOMEM;
184 }
185 if (skb->sk)
186 skb_set_owner_w(skb2, skb->sk);
187 kfree_skb(skb);
188 skb = skb2;
189 }
190
191 nf_reset(skb);
192
193 if (hh) {
194 int hh_alen;
195
196 read_lock_bh(&hh->hh_lock);
197 hh_alen = HH_DATA_ALIGN(hh->hh_len);
198 memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
199 read_unlock_bh(&hh->hh_lock);
200 skb_push(skb, hh->hh_len);
201 return hh->hh_output(skb);
202 } else if (dst->neighbour)
203 return dst->neighbour->output(skb);
204
205 if (net_ratelimit())
206 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
207 kfree_skb(skb);
208 return -EINVAL;
209 }
210
211 int ip_finish_output(struct sk_buff *skb)
212 {
213 struct net_device *dev = skb->dst->dev;
214
215 skb->dev = dev;
216 skb->protocol = htons(ETH_P_IP);
217
218 return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
219 ip_finish_output2);
220 }
221
222 int ip_mc_output(struct sk_buff *skb)
223 {
224 struct sock *sk = skb->sk;
225 struct rtable *rt = (struct rtable*)skb->dst;
226 struct net_device *dev = rt->u.dst.dev;
227
228 /*
229 * If the indicated interface is up and running, send the packet.
230 */
231 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
232
233 skb->dev = dev;
234 skb->protocol = htons(ETH_P_IP);
235
236 /*
237 * Multicasts are looped back for other local users
238 */
239
240 if (rt->rt_flags&RTCF_MULTICAST) {
241 if ((!sk || inet_sk(sk)->mc_loop)
242 #ifdef CONFIG_IP_MROUTE
243 /* Small optimization: do not loopback not local frames,
244 which returned after forwarding; they will be dropped
245 by ip_mr_input in any case.
246 Note, that local frames are looped back to be delivered
247 to local recipients.
248
249 This check is duplicated in ip_mr_input at the moment.
250 */
251 && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
252 #endif
253 ) {
254 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
255 if (newskb)
256 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
257 newskb->dev,
258 ip_dev_loopback_xmit);
259 }
260
261 /* Multicasts with ttl 0 must not go beyond the host */
262
263 if (skb->nh.iph->ttl == 0) {
264 kfree_skb(skb);
265 return 0;
266 }
267 }
268
269 if (rt->rt_flags&RTCF_BROADCAST) {
270 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
271 if (newskb)
272 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
273 newskb->dev, ip_dev_loopback_xmit);
274 }
275
276 if (skb->len > dst_mtu(&rt->u.dst))
277 return ip_fragment(skb, ip_finish_output);
278 else
279 return ip_finish_output(skb);
280 }
281
282 int ip_output(struct sk_buff *skb)
283 {
284 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
285
286 if (skb->len > dst_mtu(skb->dst) && !skb_shinfo(skb)->tso_size)
287 return ip_fragment(skb, ip_finish_output);
288 else
289 return ip_finish_output(skb);
290 }
291
292 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
293 {
294 struct sock *sk = skb->sk;
295 struct inet_sock *inet = inet_sk(sk);
296 struct ip_options *opt = inet->opt;
297 struct rtable *rt;
298 struct iphdr *iph;
299
300 /* Skip all of this if the packet is already routed,
301 * f.e. by something like SCTP.
302 */
303 rt = (struct rtable *) skb->dst;
304 if (rt != NULL)
305 goto packet_routed;
306
307 /* Make sure we can route this packet. */
308 rt = (struct rtable *)__sk_dst_check(sk, 0);
309 if (rt == NULL) {
310 u32 daddr;
311
312 /* Use correct destination address if we have options. */
313 daddr = inet->daddr;
314 if(opt && opt->srr)
315 daddr = opt->faddr;
316
317 {
318 struct flowi fl = { .oif = sk->sk_bound_dev_if,
319 .nl_u = { .ip4_u =
320 { .daddr = daddr,
321 .saddr = inet->saddr,
322 .tos = RT_CONN_FLAGS(sk) } },
323 .proto = sk->sk_protocol,
324 .uli_u = { .ports =
325 { .sport = inet->sport,
326 .dport = inet->dport } } };
327
328 /* If this fails, retransmit mechanism of transport layer will
329 * keep trying until route appears or the connection times
330 * itself out.
331 */
332 if (ip_route_output_flow(&rt, &fl, sk, 0))
333 goto no_route;
334 }
335 __sk_dst_set(sk, &rt->u.dst);
336 tcp_v4_setup_caps(sk, &rt->u.dst);
337 }
338 skb->dst = dst_clone(&rt->u.dst);
339
340 packet_routed:
341 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
342 goto no_route;
343
344 /* OK, we know where to send it, allocate and build IP header. */
345 iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
346 *((__u16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
347 iph->tot_len = htons(skb->len);
348 if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
349 iph->frag_off = htons(IP_DF);
350 else
351 iph->frag_off = 0;
352 iph->ttl = ip_select_ttl(inet, &rt->u.dst);
353 iph->protocol = sk->sk_protocol;
354 iph->saddr = rt->rt_src;
355 iph->daddr = rt->rt_dst;
356 skb->nh.iph = iph;
357 /* Transport layer set skb->h.foo itself. */
358
359 if (opt && opt->optlen) {
360 iph->ihl += opt->optlen >> 2;
361 ip_options_build(skb, opt, inet->daddr, rt, 0);
362 }
363
364 ip_select_ident_more(iph, &rt->u.dst, sk, skb_shinfo(skb)->tso_segs);
365
366 /* Add an IP checksum. */
367 ip_send_check(iph);
368
369 skb->priority = sk->sk_priority;
370
371 return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
372 dst_output);
373
374 no_route:
375 IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
376 kfree_skb(skb);
377 return -EHOSTUNREACH;
378 }
379
380
381 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
382 {
383 to->pkt_type = from->pkt_type;
384 to->priority = from->priority;
385 to->protocol = from->protocol;
386 to->security = from->security;
387 dst_release(to->dst);
388 to->dst = dst_clone(from->dst);
389 to->dev = from->dev;
390
391 /* Copy the flags to each fragment. */
392 IPCB(to)->flags = IPCB(from)->flags;
393
394 #ifdef CONFIG_NET_SCHED
395 to->tc_index = from->tc_index;
396 #endif
397 #ifdef CONFIG_NETFILTER
398 to->nfmark = from->nfmark;
399 to->nfcache = from->nfcache;
400 /* Connection association is same as pre-frag packet */
401 nf_conntrack_put(to->nfct);
402 to->nfct = from->nfct;
403 nf_conntrack_get(to->nfct);
404 to->nfctinfo = from->nfctinfo;
405 #ifdef CONFIG_BRIDGE_NETFILTER
406 nf_bridge_put(to->nf_bridge);
407 to->nf_bridge = from->nf_bridge;
408 nf_bridge_get(to->nf_bridge);
409 #endif
410 #endif
411 }
412
413 /*
414 * This IP datagram is too large to be sent in one piece. Break it up into
415 * smaller pieces (each of size equal to IP header plus
416 * a block of the data of the original IP data part) that will yet fit in a
417 * single device frame, and queue such a frame for sending.
418 */
419
420 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
421 {
422 struct iphdr *iph;
423 int raw = 0;
424 int ptr;
425 struct net_device *dev;
426 struct sk_buff *skb2;
427 unsigned int mtu, hlen, left, len, ll_rs;
428 int offset;
429 int not_last_frag;
430 struct rtable *rt = (struct rtable*)skb->dst;
431 int err = 0;
432
433 dev = rt->u.dst.dev;
434
435 /*
436 * Point into the IP datagram header.
437 */
438
439 iph = skb->nh.iph;
440
441 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
442 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
443 htonl(dst_mtu(&rt->u.dst)));
444 kfree_skb(skb);
445 return -EMSGSIZE;
446 }
447
448 /*
449 * Setup starting values.
450 */
451
452 hlen = iph->ihl * 4;
453 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */
454
455 /* When frag_list is given, use it. First, check its validity:
456 * some transformers could create wrong frag_list or break existing
457 * one, it is not prohibited. In this case fall back to copying.
458 *
459 * LATER: this step can be merged to real generation of fragments,
460 * we can switch to copy when see the first bad fragment.
461 */
462 if (skb_shinfo(skb)->frag_list) {
463 struct sk_buff *frag;
464 int first_len = skb_pagelen(skb);
465
466 if (first_len - hlen > mtu ||
467 ((first_len - hlen) & 7) ||
468 (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
469 skb_cloned(skb))
470 goto slow_path;
471
472 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
473 /* Correct geometry. */
474 if (frag->len > mtu ||
475 ((frag->len & 7) && frag->next) ||
476 skb_headroom(frag) < hlen)
477 goto slow_path;
478
479 /* Partially cloned skb? */
480 if (skb_shared(frag))
481 goto slow_path;
482
483 BUG_ON(frag->sk);
484 if (skb->sk) {
485 sock_hold(skb->sk);
486 frag->sk = skb->sk;
487 frag->destructor = sock_wfree;
488 skb->truesize -= frag->truesize;
489 }
490 }
491
492 /* Everything is OK. Generate! */
493
494 err = 0;
495 offset = 0;
496 frag = skb_shinfo(skb)->frag_list;
497 skb_shinfo(skb)->frag_list = NULL;
498 skb->data_len = first_len - skb_headlen(skb);
499 skb->len = first_len;
500 iph->tot_len = htons(first_len);
501 iph->frag_off = htons(IP_MF);
502 ip_send_check(iph);
503
504 for (;;) {
505 /* Prepare header of the next frame,
506 * before previous one went down. */
507 if (frag) {
508 frag->ip_summed = CHECKSUM_NONE;
509 frag->h.raw = frag->data;
510 frag->nh.raw = __skb_push(frag, hlen);
511 memcpy(frag->nh.raw, iph, hlen);
512 iph = frag->nh.iph;
513 iph->tot_len = htons(frag->len);
514 ip_copy_metadata(frag, skb);
515 if (offset == 0)
516 ip_options_fragment(frag);
517 offset += skb->len - hlen;
518 iph->frag_off = htons(offset>>3);
519 if (frag->next != NULL)
520 iph->frag_off |= htons(IP_MF);
521 /* Ready, complete checksum */
522 ip_send_check(iph);
523 }
524
525 err = output(skb);
526
527 if (err || !frag)
528 break;
529
530 skb = frag;
531 frag = skb->next;
532 skb->next = NULL;
533 }
534
535 if (err == 0) {
536 IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
537 return 0;
538 }
539
540 while (frag) {
541 skb = frag->next;
542 kfree_skb(frag);
543 frag = skb;
544 }
545 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
546 return err;
547 }
548
549 slow_path:
550 left = skb->len - hlen; /* Space per frame */
551 ptr = raw + hlen; /* Where to start from */
552
553 #ifdef CONFIG_BRIDGE_NETFILTER
554 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
555 * we need to make room for the encapsulating header */
556 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, nf_bridge_pad(skb));
557 mtu -= nf_bridge_pad(skb);
558 #else
559 ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev);
560 #endif
561 /*
562 * Fragment the datagram.
563 */
564
565 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
566 not_last_frag = iph->frag_off & htons(IP_MF);
567
568 /*
569 * Keep copying data until we run out.
570 */
571
572 while(left > 0) {
573 len = left;
574 /* IF: it doesn't fit, use 'mtu' - the data space left */
575 if (len > mtu)
576 len = mtu;
577 /* IF: we are not sending upto and including the packet end
578 then align the next start on an eight byte boundary */
579 if (len < left) {
580 len &= ~7;
581 }
582 /*
583 * Allocate buffer.
584 */
585
586 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
587 NETDEBUG(printk(KERN_INFO "IP: frag: no memory for new fragment!\n"));
588 err = -ENOMEM;
589 goto fail;
590 }
591
592 /*
593 * Set up data on packet
594 */
595
596 ip_copy_metadata(skb2, skb);
597 skb_reserve(skb2, ll_rs);
598 skb_put(skb2, len + hlen);
599 skb2->nh.raw = skb2->data;
600 skb2->h.raw = skb2->data + hlen;
601
602 /*
603 * Charge the memory for the fragment to any owner
604 * it might possess
605 */
606
607 if (skb->sk)
608 skb_set_owner_w(skb2, skb->sk);
609
610 /*
611 * Copy the packet header into the new buffer.
612 */
613
614 memcpy(skb2->nh.raw, skb->data, hlen);
615
616 /*
617 * Copy a block of the IP datagram.
618 */
619 if (skb_copy_bits(skb, ptr, skb2->h.raw, len))
620 BUG();
621 left -= len;
622
623 /*
624 * Fill in the new header fields.
625 */
626 iph = skb2->nh.iph;
627 iph->frag_off = htons((offset >> 3));
628
629 /* ANK: dirty, but effective trick. Upgrade options only if
630 * the segment to be fragmented was THE FIRST (otherwise,
631 * options are already fixed) and make it ONCE
632 * on the initial skb, so that all the following fragments
633 * will inherit fixed options.
634 */
635 if (offset == 0)
636 ip_options_fragment(skb);
637
638 /*
639 * Added AC : If we are fragmenting a fragment that's not the
640 * last fragment then keep MF on each bit
641 */
642 if (left > 0 || not_last_frag)
643 iph->frag_off |= htons(IP_MF);
644 ptr += len;
645 offset += len;
646
647 /*
648 * Put this fragment into the sending queue.
649 */
650
651 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
652
653 iph->tot_len = htons(len + hlen);
654
655 ip_send_check(iph);
656
657 err = output(skb2);
658 if (err)
659 goto fail;
660 }
661 kfree_skb(skb);
662 IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
663 return err;
664
665 fail:
666 kfree_skb(skb);
667 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
668 return err;
669 }
670
671 int
672 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
673 {
674 struct iovec *iov = from;
675
676 if (skb->ip_summed == CHECKSUM_HW) {
677 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
678 return -EFAULT;
679 } else {
680 unsigned int csum = 0;
681 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
682 return -EFAULT;
683 skb->csum = csum_block_add(skb->csum, csum, odd);
684 }
685 return 0;
686 }
687
688 static inline unsigned int
689 csum_page(struct page *page, int offset, int copy)
690 {
691 char *kaddr;
692 unsigned int csum;
693 kaddr = kmap(page);
694 csum = csum_partial(kaddr + offset, copy, 0);
695 kunmap(page);
696 return csum;
697 }
698
699 /*
700 * ip_append_data() and ip_append_page() can make one large IP datagram
701 * from many pieces of data. Each pieces will be holded on the socket
702 * until ip_push_pending_frames() is called. Each piece can be a page
703 * or non-page data.
704 *
705 * Not only UDP, other transport protocols - e.g. raw sockets - can use
706 * this interface potentially.
707 *
708 * LATER: length must be adjusted by pad at tail, when it is required.
709 */
710 int ip_append_data(struct sock *sk,
711 int getfrag(void *from, char *to, int offset, int len,
712 int odd, struct sk_buff *skb),
713 void *from, int length, int transhdrlen,
714 struct ipcm_cookie *ipc, struct rtable *rt,
715 unsigned int flags)
716 {
717 struct inet_sock *inet = inet_sk(sk);
718 struct sk_buff *skb;
719
720 struct ip_options *opt = NULL;
721 int hh_len;
722 int exthdrlen;
723 int mtu;
724 int copy;
725 int err;
726 int offset = 0;
727 unsigned int maxfraglen, fragheaderlen;
728 int csummode = CHECKSUM_NONE;
729
730 if (flags&MSG_PROBE)
731 return 0;
732
733 if (skb_queue_empty(&sk->sk_write_queue)) {
734 /*
735 * setup for corking.
736 */
737 opt = ipc->opt;
738 if (opt) {
739 if (inet->cork.opt == NULL) {
740 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
741 if (unlikely(inet->cork.opt == NULL))
742 return -ENOBUFS;
743 }
744 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
745 inet->cork.flags |= IPCORK_OPT;
746 inet->cork.addr = ipc->addr;
747 }
748 dst_hold(&rt->u.dst);
749 inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path);
750 inet->cork.rt = rt;
751 inet->cork.length = 0;
752 sk->sk_sndmsg_page = NULL;
753 sk->sk_sndmsg_off = 0;
754 if ((exthdrlen = rt->u.dst.header_len) != 0) {
755 length += exthdrlen;
756 transhdrlen += exthdrlen;
757 }
758 } else {
759 rt = inet->cork.rt;
760 if (inet->cork.flags & IPCORK_OPT)
761 opt = inet->cork.opt;
762
763 transhdrlen = 0;
764 exthdrlen = 0;
765 mtu = inet->cork.fragsize;
766 }
767 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
768
769 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
770 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
771
772 if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
773 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
774 return -EMSGSIZE;
775 }
776
777 /*
778 * transhdrlen > 0 means that this is the first fragment and we wish
779 * it won't be fragmented in the future.
780 */
781 if (transhdrlen &&
782 length + fragheaderlen <= mtu &&
783 rt->u.dst.dev->features&(NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM) &&
784 !exthdrlen)
785 csummode = CHECKSUM_HW;
786
787 inet->cork.length += length;
788
789 /* So, what's going on in the loop below?
790 *
791 * We use calculated fragment length to generate chained skb,
792 * each of segments is IP fragment ready for sending to network after
793 * adding appropriate IP header.
794 */
795
796 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
797 goto alloc_new_skb;
798
799 while (length > 0) {
800 /* Check if the remaining data fits into current packet. */
801 copy = mtu - skb->len;
802 if (copy < length)
803 copy = maxfraglen - skb->len;
804 if (copy <= 0) {
805 char *data;
806 unsigned int datalen;
807 unsigned int fraglen;
808 unsigned int fraggap;
809 unsigned int alloclen;
810 struct sk_buff *skb_prev;
811 alloc_new_skb:
812 skb_prev = skb;
813 if (skb_prev)
814 fraggap = skb_prev->len - maxfraglen;
815 else
816 fraggap = 0;
817
818 /*
819 * If remaining data exceeds the mtu,
820 * we know we need more fragment(s).
821 */
822 datalen = length + fraggap;
823 if (datalen > mtu - fragheaderlen)
824 datalen = maxfraglen - fragheaderlen;
825 fraglen = datalen + fragheaderlen;
826
827 if ((flags & MSG_MORE) &&
828 !(rt->u.dst.dev->features&NETIF_F_SG))
829 alloclen = mtu;
830 else
831 alloclen = datalen + fragheaderlen;
832
833 /* The last fragment gets additional space at tail.
834 * Note, with MSG_MORE we overallocate on fragments,
835 * because we have no idea what fragment will be
836 * the last.
837 */
838 if (datalen == length)
839 alloclen += rt->u.dst.trailer_len;
840
841 if (transhdrlen) {
842 skb = sock_alloc_send_skb(sk,
843 alloclen + hh_len + 15,
844 (flags & MSG_DONTWAIT), &err);
845 } else {
846 skb = NULL;
847 if (atomic_read(&sk->sk_wmem_alloc) <=
848 2 * sk->sk_sndbuf)
849 skb = sock_wmalloc(sk,
850 alloclen + hh_len + 15, 1,
851 sk->sk_allocation);
852 if (unlikely(skb == NULL))
853 err = -ENOBUFS;
854 }
855 if (skb == NULL)
856 goto error;
857
858 /*
859 * Fill in the control structures
860 */
861 skb->ip_summed = csummode;
862 skb->csum = 0;
863 skb_reserve(skb, hh_len);
864
865 /*
866 * Find where to start putting bytes.
867 */
868 data = skb_put(skb, fraglen);
869 skb->nh.raw = data + exthdrlen;
870 data += fragheaderlen;
871 skb->h.raw = data + exthdrlen;
872
873 if (fraggap) {
874 skb->csum = skb_copy_and_csum_bits(
875 skb_prev, maxfraglen,
876 data + transhdrlen, fraggap, 0);
877 skb_prev->csum = csum_sub(skb_prev->csum,
878 skb->csum);
879 data += fraggap;
880 skb_trim(skb_prev, maxfraglen);
881 }
882
883 copy = datalen - transhdrlen - fraggap;
884 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
885 err = -EFAULT;
886 kfree_skb(skb);
887 goto error;
888 }
889
890 offset += copy;
891 length -= datalen - fraggap;
892 transhdrlen = 0;
893 exthdrlen = 0;
894 csummode = CHECKSUM_NONE;
895
896 /*
897 * Put the packet on the pending queue.
898 */
899 __skb_queue_tail(&sk->sk_write_queue, skb);
900 continue;
901 }
902
903 if (copy > length)
904 copy = length;
905
906 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
907 unsigned int off;
908
909 off = skb->len;
910 if (getfrag(from, skb_put(skb, copy),
911 offset, copy, off, skb) < 0) {
912 __skb_trim(skb, off);
913 err = -EFAULT;
914 goto error;
915 }
916 } else {
917 int i = skb_shinfo(skb)->nr_frags;
918 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
919 struct page *page = sk->sk_sndmsg_page;
920 int off = sk->sk_sndmsg_off;
921 unsigned int left;
922
923 if (page && (left = PAGE_SIZE - off) > 0) {
924 if (copy >= left)
925 copy = left;
926 if (page != frag->page) {
927 if (i == MAX_SKB_FRAGS) {
928 err = -EMSGSIZE;
929 goto error;
930 }
931 get_page(page);
932 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
933 frag = &skb_shinfo(skb)->frags[i];
934 }
935 } else if (i < MAX_SKB_FRAGS) {
936 if (copy > PAGE_SIZE)
937 copy = PAGE_SIZE;
938 page = alloc_pages(sk->sk_allocation, 0);
939 if (page == NULL) {
940 err = -ENOMEM;
941 goto error;
942 }
943 sk->sk_sndmsg_page = page;
944 sk->sk_sndmsg_off = 0;
945
946 skb_fill_page_desc(skb, i, page, 0, 0);
947 frag = &skb_shinfo(skb)->frags[i];
948 skb->truesize += PAGE_SIZE;
949 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
950 } else {
951 err = -EMSGSIZE;
952 goto error;
953 }
954 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
955 err = -EFAULT;
956 goto error;
957 }
958 sk->sk_sndmsg_off += copy;
959 frag->size += copy;
960 skb->len += copy;
961 skb->data_len += copy;
962 }
963 offset += copy;
964 length -= copy;
965 }
966
967 return 0;
968
969 error:
970 inet->cork.length -= length;
971 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
972 return err;
973 }
974
975 ssize_t ip_append_page(struct sock *sk, struct page *page,
976 int offset, size_t size, int flags)
977 {
978 struct inet_sock *inet = inet_sk(sk);
979 struct sk_buff *skb;
980 struct rtable *rt;
981 struct ip_options *opt = NULL;
982 int hh_len;
983 int mtu;
984 int len;
985 int err;
986 unsigned int maxfraglen, fragheaderlen, fraggap;
987
988 if (inet->hdrincl)
989 return -EPERM;
990
991 if (flags&MSG_PROBE)
992 return 0;
993
994 if (skb_queue_empty(&sk->sk_write_queue))
995 return -EINVAL;
996
997 rt = inet->cork.rt;
998 if (inet->cork.flags & IPCORK_OPT)
999 opt = inet->cork.opt;
1000
1001 if (!(rt->u.dst.dev->features&NETIF_F_SG))
1002 return -EOPNOTSUPP;
1003
1004 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1005 mtu = inet->cork.fragsize;
1006
1007 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1008 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1009
1010 if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1011 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
1012 return -EMSGSIZE;
1013 }
1014
1015 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1016 return -EINVAL;
1017
1018 inet->cork.length += size;
1019
1020 while (size > 0) {
1021 int i;
1022
1023 /* Check if the remaining data fits into current packet. */
1024 len = mtu - skb->len;
1025 if (len < size)
1026 len = maxfraglen - skb->len;
1027 if (len <= 0) {
1028 struct sk_buff *skb_prev;
1029 char *data;
1030 struct iphdr *iph;
1031 int alloclen;
1032
1033 skb_prev = skb;
1034 if (skb_prev)
1035 fraggap = skb_prev->len - maxfraglen;
1036 else
1037 fraggap = 0;
1038
1039 alloclen = fragheaderlen + hh_len + fraggap + 15;
1040 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1041 if (unlikely(!skb)) {
1042 err = -ENOBUFS;
1043 goto error;
1044 }
1045
1046 /*
1047 * Fill in the control structures
1048 */
1049 skb->ip_summed = CHECKSUM_NONE;
1050 skb->csum = 0;
1051 skb_reserve(skb, hh_len);
1052
1053 /*
1054 * Find where to start putting bytes.
1055 */
1056 data = skb_put(skb, fragheaderlen + fraggap);
1057 skb->nh.iph = iph = (struct iphdr *)data;
1058 data += fragheaderlen;
1059 skb->h.raw = data;
1060
1061 if (fraggap) {
1062 skb->csum = skb_copy_and_csum_bits(
1063 skb_prev, maxfraglen,
1064 data, fraggap, 0);
1065 skb_prev->csum = csum_sub(skb_prev->csum,
1066 skb->csum);
1067 skb_trim(skb_prev, maxfraglen);
1068 }
1069
1070 /*
1071 * Put the packet on the pending queue.
1072 */
1073 __skb_queue_tail(&sk->sk_write_queue, skb);
1074 continue;
1075 }
1076
1077 i = skb_shinfo(skb)->nr_frags;
1078 if (len > size)
1079 len = size;
1080 if (skb_can_coalesce(skb, i, page, offset)) {
1081 skb_shinfo(skb)->frags[i-1].size += len;
1082 } else if (i < MAX_SKB_FRAGS) {
1083 get_page(page);
1084 skb_fill_page_desc(skb, i, page, offset, len);
1085 } else {
1086 err = -EMSGSIZE;
1087 goto error;
1088 }
1089
1090 if (skb->ip_summed == CHECKSUM_NONE) {
1091 unsigned int csum;
1092 csum = csum_page(page, offset, len);
1093 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1094 }
1095
1096 skb->len += len;
1097 skb->data_len += len;
1098 offset += len;
1099 size -= len;
1100 }
1101 return 0;
1102
1103 error:
1104 inet->cork.length -= size;
1105 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1106 return err;
1107 }
1108
1109 /*
1110 * Combined all pending IP fragments on the socket as one IP datagram
1111 * and push them out.
1112 */
1113 int ip_push_pending_frames(struct sock *sk)
1114 {
1115 struct sk_buff *skb, *tmp_skb;
1116 struct sk_buff **tail_skb;
1117 struct inet_sock *inet = inet_sk(sk);
1118 struct ip_options *opt = NULL;
1119 struct rtable *rt = inet->cork.rt;
1120 struct iphdr *iph;
1121 int df = 0;
1122 __u8 ttl;
1123 int err = 0;
1124
1125 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1126 goto out;
1127 tail_skb = &(skb_shinfo(skb)->frag_list);
1128
1129 /* move skb->data to ip header from ext header */
1130 if (skb->data < skb->nh.raw)
1131 __skb_pull(skb, skb->nh.raw - skb->data);
1132 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1133 __skb_pull(tmp_skb, skb->h.raw - skb->nh.raw);
1134 *tail_skb = tmp_skb;
1135 tail_skb = &(tmp_skb->next);
1136 skb->len += tmp_skb->len;
1137 skb->data_len += tmp_skb->len;
1138 skb->truesize += tmp_skb->truesize;
1139 __sock_put(tmp_skb->sk);
1140 tmp_skb->destructor = NULL;
1141 tmp_skb->sk = NULL;
1142 }
1143
1144 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1145 * to fragment the frame generated here. No matter, what transforms
1146 * how transforms change size of the packet, it will come out.
1147 */
1148 if (inet->pmtudisc != IP_PMTUDISC_DO)
1149 skb->local_df = 1;
1150
1151 /* DF bit is set when we want to see DF on outgoing frames.
1152 * If local_df is set too, we still allow to fragment this frame
1153 * locally. */
1154 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1155 (skb->len <= dst_mtu(&rt->u.dst) &&
1156 ip_dont_fragment(sk, &rt->u.dst)))
1157 df = htons(IP_DF);
1158
1159 if (inet->cork.flags & IPCORK_OPT)
1160 opt = inet->cork.opt;
1161
1162 if (rt->rt_type == RTN_MULTICAST)
1163 ttl = inet->mc_ttl;
1164 else
1165 ttl = ip_select_ttl(inet, &rt->u.dst);
1166
1167 iph = (struct iphdr *)skb->data;
1168 iph->version = 4;
1169 iph->ihl = 5;
1170 if (opt) {
1171 iph->ihl += opt->optlen>>2;
1172 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1173 }
1174 iph->tos = inet->tos;
1175 iph->tot_len = htons(skb->len);
1176 iph->frag_off = df;
1177 if (!df) {
1178 __ip_select_ident(iph, &rt->u.dst, 0);
1179 } else {
1180 iph->id = htons(inet->id++);
1181 }
1182 iph->ttl = ttl;
1183 iph->protocol = sk->sk_protocol;
1184 iph->saddr = rt->rt_src;
1185 iph->daddr = rt->rt_dst;
1186 ip_send_check(iph);
1187
1188 skb->priority = sk->sk_priority;
1189 skb->dst = dst_clone(&rt->u.dst);
1190
1191 /* Netfilter gets whole the not fragmented skb. */
1192 err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
1193 skb->dst->dev, dst_output);
1194 if (err) {
1195 if (err > 0)
1196 err = inet->recverr ? net_xmit_errno(err) : 0;
1197 if (err)
1198 goto error;
1199 }
1200
1201 out:
1202 inet->cork.flags &= ~IPCORK_OPT;
1203 if (inet->cork.opt) {
1204 kfree(inet->cork.opt);
1205 inet->cork.opt = NULL;
1206 }
1207 if (inet->cork.rt) {
1208 ip_rt_put(inet->cork.rt);
1209 inet->cork.rt = NULL;
1210 }
1211 return err;
1212
1213 error:
1214 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1215 goto out;
1216 }
1217
1218 /*
1219 * Throw away all pending data on the socket.
1220 */
1221 void ip_flush_pending_frames(struct sock *sk)
1222 {
1223 struct inet_sock *inet = inet_sk(sk);
1224 struct sk_buff *skb;
1225
1226 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1227 kfree_skb(skb);
1228
1229 inet->cork.flags &= ~IPCORK_OPT;
1230 if (inet->cork.opt) {
1231 kfree(inet->cork.opt);
1232 inet->cork.opt = NULL;
1233 }
1234 if (inet->cork.rt) {
1235 ip_rt_put(inet->cork.rt);
1236 inet->cork.rt = NULL;
1237 }
1238 }
1239
1240
1241 /*
1242 * Fetch data from kernel space and fill in checksum if needed.
1243 */
1244 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1245 int len, int odd, struct sk_buff *skb)
1246 {
1247 unsigned int csum;
1248
1249 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1250 skb->csum = csum_block_add(skb->csum, csum, odd);
1251 return 0;
1252 }
1253
1254 /*
1255 * Generic function to send a packet as reply to another packet.
1256 * Used to send TCP resets so far. ICMP should use this function too.
1257 *
1258 * Should run single threaded per socket because it uses the sock
1259 * structure to pass arguments.
1260 *
1261 * LATER: switch from ip_build_xmit to ip_append_*
1262 */
1263 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1264 unsigned int len)
1265 {
1266 struct inet_sock *inet = inet_sk(sk);
1267 struct {
1268 struct ip_options opt;
1269 char data[40];
1270 } replyopts;
1271 struct ipcm_cookie ipc;
1272 u32 daddr;
1273 struct rtable *rt = (struct rtable*)skb->dst;
1274
1275 if (ip_options_echo(&replyopts.opt, skb))
1276 return;
1277
1278 daddr = ipc.addr = rt->rt_src;
1279 ipc.opt = NULL;
1280
1281 if (replyopts.opt.optlen) {
1282 ipc.opt = &replyopts.opt;
1283
1284 if (ipc.opt->srr)
1285 daddr = replyopts.opt.faddr;
1286 }
1287
1288 {
1289 struct flowi fl = { .nl_u = { .ip4_u =
1290 { .daddr = daddr,
1291 .saddr = rt->rt_spec_dst,
1292 .tos = RT_TOS(skb->nh.iph->tos) } },
1293 /* Not quite clean, but right. */
1294 .uli_u = { .ports =
1295 { .sport = skb->h.th->dest,
1296 .dport = skb->h.th->source } },
1297 .proto = sk->sk_protocol };
1298 if (ip_route_output_key(&rt, &fl))
1299 return;
1300 }
1301
1302 /* And let IP do all the hard work.
1303
1304 This chunk is not reenterable, hence spinlock.
1305 Note that it uses the fact, that this function is called
1306 with locally disabled BH and that sk cannot be already spinlocked.
1307 */
1308 bh_lock_sock(sk);
1309 inet->tos = skb->nh.iph->tos;
1310 sk->sk_priority = skb->priority;
1311 sk->sk_protocol = skb->nh.iph->protocol;
1312 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1313 &ipc, rt, MSG_DONTWAIT);
1314 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1315 if (arg->csumoffset >= 0)
1316 *((u16 *)skb->h.raw + arg->csumoffset) = csum_fold(csum_add(skb->csum, arg->csum));
1317 skb->ip_summed = CHECKSUM_NONE;
1318 ip_push_pending_frames(sk);
1319 }
1320
1321 bh_unlock_sock(sk);
1322
1323 ip_rt_put(rt);
1324 }
1325
1326 /*
1327 * IP protocol layer initialiser
1328 */
1329
1330 static struct packet_type ip_packet_type = {
1331 .type = __constant_htons(ETH_P_IP),
1332 .func = ip_rcv,
1333 };
1334
1335 /*
1336 * IP registers the packet type and then calls the subprotocol initialisers
1337 */
1338
1339 void __init ip_init(void)
1340 {
1341 dev_add_pack(&ip_packet_type);
1342
1343 ip_rt_init();
1344 inet_initpeers();
1345
1346 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1347 igmp_mc_proc_init();
1348 #endif
1349 }
1350
1351 EXPORT_SYMBOL(ip_finish_output);
1352 EXPORT_SYMBOL(ip_fragment);
1353 EXPORT_SYMBOL(ip_generic_getfrag);
1354 EXPORT_SYMBOL(ip_queue_xmit);
1355 EXPORT_SYMBOL(ip_send_check);
1356
1357 #ifdef CONFIG_SYSCTL
1358 EXPORT_SYMBOL(sysctl_ip_default_ttl);
1359 #endif
Linux kernel - Deliverables
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